Interest: kernel TUN overlay transport (acting as exit node / subnet router on small Linux routers)

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#486 0 comments 0 reactions 0 assignees View on GitHub

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Assessment

Difficulty
5/5
Estimated time
Over a week
Newbie friendliness
15/100
Issue type
Feature
Clarity
Needs clarification
Activity status
Active
Tech stack
linux, rust
Domain
embedded-iot, networking

Research direction

This is a proposal for a kernel TUN transport as an alternative to NetstackActor, not a defined change yet. Start by reading NetstackActor and the NewOverlayTransport channels in ts_runtime, then the Config in ts_control where HostInfo.RoutableIPs would be set. Done means the maintainers have agreed on a direction and it has been split into small PRs, so wait for their reply before writing code.

Written by the indexing model from the issue text.

Description

#405 covers using an exit node. We built the opposite on top of tailscale-rs, for small routers where Go tailscaled gets OOM-killed (MikroTik mAP lite: MIPS 24Kc, 64 MB RAM, 16 MB flash):

  • a TunActor as an alternative to NetstackActor, using the same NewOverlayTransport channels (kernel TUN, batched reads with backpressure);
  • HostInfo.RoutableIPs sent from ts_control::Config;
  • extra inbound routes (0.0.0.0/0, ::/0) in the route updater;
  • netstack made an optional feature of ts_runtime.

The kernel does forwarding and NAT. Result on the mAP lite: ~11 Mbit/s, ~8.6 MB peak RSS, about 3 MB on flash (static musl, opt-level = "z"). Tested against a lab Headscale + derper; related fixes reported in #481, #439 and #485.

Would you be interested in this direction? If so, we could split it into small PRs following CONTRIBUTING.

AI disclosure: the code was written with an AI assistant (Claude) under human direction. It was tested on a lab tailnet and on real hardware.

Dominant language
Rust
Stars
1.2k
Forks
75
Avg merge
1d 13h
Merged PRs (30d)
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